Stephen Hawking has told One Direction fans to pay close attention to theoretical physics because it might come up with proof of an alternative universe in which Zayn Malik is still in the band.

The physicist and cosmologist appeared in holographic form at the Sydney Opera House on Saturday, streamed in from Cambridge University in the UK.

Asked about the cosmological effect of Malik leaving One Direction, Hawking advised any heartbroken young girls: “One day there may well be proof of multiple universes … and in that universe Zayn is still in One Direction.”

He was joined by his daughter and science communicator Lucy Hawking and the physicist Paul Davies, who were live on stage in Sydney.

Of his portrayal in the Academy award-winning film The Theory of Everything, Hawking said he had been apprehensive about the project because it was based on a book by his former wife, Jane Wilde, but had been reassured when he read the script and attended a screening.

“It was surprisingly honest about our marriage,” said Hawking, who also approved of actor Eddie Redmayne’s portrayal of him. “It was as close as I’ll ever get to travelling back in time.”

Any departures by the production company from the true story were minor, Hawking said. “I won’t tell them how to make movies, if they don’t tell me how to solve the mysteries of the universe.” And while he felt the film should have had “more physics and fewer feelings”, he said that was how he felt about all films.

In a wide-ranging discussion, Hawking said contemporary society had an “ambivalent attitude” to science. “We have come to expect a steady increase in standard of living that science and technology have brought. But people distrust science because they don’t understand it or feel they can control it.

“The popularity of science fiction like Star Trek is because this is a form of science with which people feel safe, but an understanding of science fact would allay their fears … much better.”

Fascination with science, argued Hawking, needed to be harnessed to help the public make informed decisions on matters such as the greenhouse effect, nuclear weapons and genetic engineering.

Hawking said he had been surprised by the popularity of his bestselling book A Brief History of Time. While writing it he had been told each equation he included would halve sales. “I included one – Einstein’s famous E=MC2. Perhaps I would have sold twice as many copies without it.”

The physicist ended by quoting the Star Trek character Captain Kirk: “Now beam me up, Scotty,” after which his digital image appeared to explode in a beam of light.